Acrosomal alkalization triggers Ca2+ release and acrosome reaction in mammalian spermatozoa

• DOI: 10.1002/jcp.26262
• Publication Date: 2017-11-14T13:26:44Z
• Authors: Julio C. Chávez; José L. De la Veg...; Omar José; Paulina Torres; Takuya Nishigaki; Claudia L. Treviño; Alberto Darszon
• Keywords: Acrosome reaction; Capacitation; Ionomycin

The sperm acrosome reaction (AR), an essential event for mammalian fertilization, involves Ca 2+ permeability changes leading to exocytosis of the acrosomal vesicle. acrosome, intracellular store whose luminal pH is acidic, contains hydrolytic enzymes. It known that (pH acr ) increases during capacitation and this correlates with spontaneous AR. Some AR inducers increase concentration ([Ca ] i through release from internal stores, mainly acrosome. Catsper, a specific channel, has been suggested participate in Curiously, Mibefradil NNC55‐0396, two CatSper blockers, themselves elevate [Ca by unknown mechanisms. Here we show these compounds, as other weak bases, can , trigger induce both mouse human sperm. To our surprise, μM concentrations NNC55‐0396 induced even nominally free media. Our findings suggest alkalization critical step leads reaction.